Antigen-presenting capacity of alveolar macrophages and monocytes in pulmonary tuberculosis

Using purified protein derivative of tuberculin (PPD) as an antigen, antigen-presenting capacity by monocytes (Mo) and alveolar macrophages (AM) was determined in 17 patients with pulmonary tuberculosis and nine healthy controls. All of the patients and healthy controls were positive for PPD skin test. Although Mo obtained from both the control and tubercular subjects revealed antigen-presenting capacity to autologous blood T-lymphocytes, no significant difference was observed between the two groups. In contrast, AM obtained from the tubercular patients, but not from the controls, showed antigen-presenting capacity to autologous blood T-lymphocytes and to lung T-lymphocytes. No significant difference was shown in HLA-DR antigen expression on AM between the control and tubercular patients. Besides, the exogenous addition of interleukin-1 (IL-1) did not induce antigen-presenting capacity by AM obtained from the controls. These results suggest that neither increased HLA-DR antigen expression on AM nor an increased release of IL-1 from AM is responsible for the enhanced antigen-presenting capacity in tuberculosis.